THREE-WAY TWO-POSITION SPOOL-TYPE DIFFERENTIAL-PILOT-OPERATED PNEUMATIC DIRECTIONAL VALVE MECHANISM

When pilot air is admitted into port 4, spool 6 is shuttled to the position shown in Fig. a, and port 1, supplied by compressed air from the main, is connected to port 2. Port 3, connected to the atmosphere, is closed off. When pilot air is admitted to port 5 without cutting off air admission to port 4, spool 6 moves to the left because the right end of spool 6 is of greater area than its left end…